This application relates to noise attenuation devices for use in induction systems, for example.
Resonators are used in induction systems for vehicle engines to provide broad noise attenuation. While resonators provide very good attenuation, it is typically desirable to supplement the noise attenuation provided by a resonator with additional noise attenuation devices, such as quarter wave tubes and/or Helmholtz resonators. Space in the engine compartment, where the resonator typically is located, is usually quite limited. As a result, it is difficult to package additional noise attenuation devices.
Resonators are typically large box-like structures providing an expansion chamber between an inlet and outlet. Due to packaging constraints, the inlet and outlet may not be in line with one another such that there is not a direct flow path through the resonator. As a result, pressure losses can occur as the air flows from the inlet to the outlet. One approach to minimizing pressure losses has been to provide an arcuate tube within the resonator and extending between the inlet and outlet, which are arranged at an angle relative to one another. The two-piece resonator includes one portion that provides one half of the arcuate tube. Another arcuate portion is secured over the half of the arcuate tube to connect the inlet and outlet. A series of elongated slots are provided near where the tube halves meet at both the inner and outer radius of the arcuate tube. A cover of the resonator is secured over the first portion to enclose the arcuate tube and provide the enclosed resonator cavity. The arcuate tube is intended to minimize pressure losses as the air flows between the inlet and outlet. The elongated slots are intended to take advantage of the resonator by providing fluid communication between the air within the arcuate tube and the resonator cavity. However, desired noise attenuation has not been achieved with this arrangement.
What is needed is an improved resonator with desired flow characteristics. What is also needed is supplemental noise attenuation requiring minimal space.